Machine tools are usually adapted for being used with many different tool sets. A typical tool set includes a punch and a corresponding die. A stripper plate is also commonly included as part of the tool set. In processing a workpiece (e.g., a piece of sheet metal), it is common to use several different tool sets. In some cases, once a first tool set has been used, it is exchanged for a second tool set, and then a third, and so on. Once a first workpiece has been fully processed using the desired sequence of tool sets, a second workpiece may be processed, in some cases beginning again with the first tool set.
The tool sets used on a machine tool commonly are stored in cartridges. Some cartridges may be stored in the machine tool, while others may be kept nearby. When several different tool sets (e.g., of different size and/or shape) will be used for a job, the machine tool is commonly provided with cartridges respectively holding the different tool sets. Not only do the cartridges store the tools, they also facilitate loading and unloading the tools on the machine tool. For example, when it is desired to use a particular tool set, a cartridge holding that tool set is moved to a mounting position on the machine tool. At the mounting position, the tools are removed from the cartridge and loaded onto the machine tool. Once use of that tool set is finished, its tools are unloaded from the machine tool and loaded back onto the cartridge. The cartridge is then moved away from the mounting position. Then, a different cartridge (holding another tool set) can be moved to the mounting position so that a new set of tools can be used by the machine tool. This process is repeated for as many different tool sets as are needed for a given job. In some cases, the machine tool includes an elongated rail for storing the cartridges. The cartridges, for example, can be slidably engaged with the rail such that they can be slid back and forth to and from the mounting position. In other cases, the cartridges are stored in a rotary storage system, a round carousel, or a stacked storage system. The mounting and dismounting of tool sets using cartridges is described in U.S. Pat. No. 4,951,375. This '375 patent is incorporated herein by reference to the extent it shows and describes the structure of an exemplary machine tool with a cartridge guidance system.
Since cartridges are moved by the machine tool, there is often wear and tear on the cartridges. This can result in cartridge breakage. Cartridges have been made of cast iron, so as to minimize breakage. However, these cast iron cartridges are very heavy. As a result, they are less than ideal in terms of their great inertia, which adversely impacts the dynamic performance of a machine tool in loading, unloading, and otherwise moving the cartridges. Heavy cartridges also cause unnecessary wear and tear on the machine tool. Due to these problems, plastic/composite cartridges have been used as an alternative. These cartridges are lighter and cheaper to manufacture. They also impose less wear and tear on the machine tool. However, these cartridges are still quite prone to breakage. While steel has been used for the cartridge arms that hold the punches and dies, these cartridges are nowhere near as strong and durable as the cast iron cartridges.
There is a need for a cartridge that is durable and resistant to breakage, while also being light enough to facilitate swift cartridge movements and/or to reduce wear and tear on the machine tool. It would also be desirable to provide cartridges that have one or more removable high-wear-location inserts. Further, it would be desirable to provide a cartridge with one or more coatings to improve the cartridge's performance and/or durability. Still further, it would be desirable to provide a cartridge having selected portions formed of particular metals, non-metals, and/or composites that improve the cartridge's performance and/or durability. Finally, it would be desirable to provide a metal cartridge having a weight approximating that of a conventional plastic cartridge.